Semiconductor laser devices are known that have an epitaxial semiconductor body with a waveguiding layer, which contains an active radiation-generating layer, a laser-active emitter region, disposed in the epitaxial semiconductor body and having a primary light projection direction (referred to herein as the “primary direction”), which essentially corresponds to the exit direction of the laser radiation from the emitter region, and an amplifier region, adjoining the emitter region in the semiconductor body in the primary direction, for amplifying the laser radiation. The emitter region and the amplifier region form active regions in the semiconductor material.
Semiconductor lasers of this kind are used as light sources of high brilliance. Because of the high intensities, however, there is the problem that scattered light, or light backscattered (used interchangeably herein with backreflected) into the active region, interferes with the desired laser emission and/or makes the beam quality worse.
Various principles are known for counteracting this problem. For instance, the facets of the active regions are made nonreflective, to suppress unwanted backreflections into the active region. Another known principle is to etch V-shaped notches into the epitaxial layers outside the active components, and to fill these notches with absorbent material.
European Patent EP-B 0 624 284 shows and describes a semiconductor laser amplifier arrangement, in which oblique notches with 45° flanks are etched into the epitaxial layers on both sides of the arrangement. Light back-reflected from the end face is meant to be reflected laterally and vertically away from the component by these notches.